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dm kcopyd: per device 

Make one kcopyd thread per device.

The original shared kcopyd could deadlock.

Configuration:
This commit is contained in:
Mikulas Patocka 2008-04-24 21:43:44 +01:00 committed by Alasdair G Kergon
parent 2a23aa1ddb
commit 8c0cbc2f79
1 changed files with 73 additions and 59 deletions
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132
drivers/md/kcopyd.c
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@ -26,14 +26,6 @@
#include "kcopyd.h"
#include "dm.h"
static struct workqueue_struct *_kcopyd_wq;
static struct work_struct _kcopyd_work;
static void wake(void)
{
queue_work(_kcopyd_wq, &_kcopyd_work);
}
/*-----------------------------------------------------------------
* Each kcopyd client has its own little pool of preallocated
* pages for kcopyd io.
@ -50,8 +42,30 @@ struct dm_kcopyd_client {
wait_queue_head_t destroyq;
atomic_t nr_jobs;
struct workqueue_struct *kcopyd_wq;
struct work_struct kcopyd_work;
/*
* We maintain three lists of jobs:
*
* i) jobs waiting for pages
* ii) jobs that have pages, and are waiting for the io to be issued.
* iii) jobs that have completed.
*
* All three of these are protected by job_lock.
*/
spinlock_t job_lock;
struct list_head complete_jobs;
struct list_head io_jobs;
struct list_head pages_jobs;
};
static void wake(struct dm_kcopyd_client *kc)
{
queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
}
static struct page_list *alloc_pl(void)
{
struct page_list *pl;
@ -209,21 +223,6 @@ struct kcopyd_job {
static struct kmem_cache *_job_cache;
static mempool_t *_job_pool;
/*
* We maintain three lists of jobs:
*
* i) jobs waiting for pages
* ii) jobs that have pages, and are waiting for the io to be issued.
* iii) jobs that have completed.
*
* All three of these are protected by job_lock.
*/
static DEFINE_SPINLOCK(_job_lock);
static LIST_HEAD(_complete_jobs);
static LIST_HEAD(_io_jobs);
static LIST_HEAD(_pages_jobs);
static int jobs_init(void)
{
_job_cache = KMEM_CACHE(kcopyd_job, 0);
@ -241,10 +240,6 @@ static int jobs_init(void)
static void jobs_exit(void)
{
BUG_ON(!list_empty(&_complete_jobs));
BUG_ON(!list_empty(&_io_jobs));
BUG_ON(!list_empty(&_pages_jobs));
mempool_destroy(_job_pool);
kmem_cache_destroy(_job_cache);
_job_pool = NULL;
@ -255,18 +250,19 @@ static void jobs_exit(void)
* Functions to push and pop a job onto the head of a given job
* list.
*/
static struct kcopyd_job *pop(struct list_head *jobs)
static struct kcopyd_job *pop(struct list_head *jobs,
struct dm_kcopyd_client *kc)
{
struct kcopyd_job *job = NULL;
unsigned long flags;
spin_lock_irqsave(&_job_lock, flags);
spin_lock_irqsave(&kc->job_lock, flags);
if (!list_empty(jobs)) {
job = list_entry(jobs->next, struct kcopyd_job, list);
list_del(&job->list);
}
spin_unlock_irqrestore(&_job_lock, flags);
spin_unlock_irqrestore(&kc->job_lock, flags);
return job;
}
@ -274,10 +270,11 @@ static struct kcopyd_job *pop(struct list_head *jobs)
static void push(struct list_head *jobs, struct kcopyd_job *job)
{
unsigned long flags;
struct dm_kcopyd_client *kc = job->kc;
spin_lock_irqsave(&_job_lock, flags);
spin_lock_irqsave(&kc->job_lock, flags);
list_add_tail(&job->list, jobs);
spin_unlock_irqrestore(&_job_lock, flags);
spin_unlock_irqrestore(&kc->job_lock, flags);
}
/*
@ -310,6 +307,7 @@ static int run_complete_job(struct kcopyd_job *job)
static void complete_io(unsigned long error, void *context)
{
struct kcopyd_job *job = (struct kcopyd_job *) context;
struct dm_kcopyd_client *kc = job->kc;
if (error) {
if (job->rw == WRITE)
@ -318,21 +316,21 @@ static void complete_io(unsigned long error, void *context)
job->read_err = 1;
if (!test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) {
push(&_complete_jobs, job);
wake();
push(&kc->complete_jobs, job);
wake(kc);
return;
}
}
if (job->rw == WRITE)
push(&_complete_jobs, job);
push(&kc->complete_jobs, job);
else {
job->rw = WRITE;
push(&_io_jobs, job);
push(&kc->io_jobs, job);
}
wake();
wake(kc);
}
/*
@ -369,7 +367,7 @@ static int run_pages_job(struct kcopyd_job *job)
r = kcopyd_get_pages(job->kc, job->nr_pages, &job->pages);
if (!r) {
/* this job is ready for io */
push(&_io_jobs, job);
push(&job->kc->io_jobs, job);
return 0;
}
@ -384,12 +382,13 @@ static int run_pages_job(struct kcopyd_job *job)
* Run through a list for as long as possible. Returns the count
* of successful jobs.
*/
static int process_jobs(struct list_head *jobs, int (*fn) (struct kcopyd_job *))
static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,
int (*fn) (struct kcopyd_job *))
{
struct kcopyd_job *job;
int r, count = 0;
while ((job = pop(jobs))) {
while ((job = pop(jobs, kc))) {
r = fn(job);
@ -399,7 +398,7 @@ static int process_jobs(struct list_head *jobs, int (*fn) (struct kcopyd_job *))
job->write_err = (unsigned long) -1L;
else
job->read_err = 1;
push(&_complete_jobs, job);
push(&kc->complete_jobs, job);
break;
}
@ -421,8 +420,11 @@ static int process_jobs(struct list_head *jobs, int (*fn) (struct kcopyd_job *))
/*
* kcopyd does this every time it's woken up.
*/
static void do_work(struct work_struct *ignored)
static void do_work(struct work_struct *work)
{
struct dm_kcopyd_client *kc = container_of(work,
struct dm_kcopyd_client, kcopyd_work);
/*
* The order that these are called is *very* important.
* complete jobs can free some pages for pages jobs.
@ -430,9 +432,9 @@ static void do_work(struct work_struct *ignored)
* list. io jobs call wake when they complete and it all
* starts again.
*/
process_jobs(&_complete_jobs, run_complete_job);
process_jobs(&_pages_jobs, run_pages_job);
process_jobs(&_io_jobs, run_io_job);
process_jobs(&kc->complete_jobs, kc, run_complete_job);
process_jobs(&kc->pages_jobs, kc, run_pages_job);
process_jobs(&kc->io_jobs, kc, run_io_job);
}
/*
@ -442,9 +444,10 @@ static void do_work(struct work_struct *ignored)
*/
static void dispatch_job(struct kcopyd_job *job)
{
atomic_inc(&job->kc->nr_jobs);
push(&_pages_jobs, job);
wake();
struct dm_kcopyd_client *kc = job->kc;
atomic_inc(&kc->nr_jobs);
push(&kc->pages_jobs, job);
wake(kc);
}
#define SUB_JOB_SIZE 128
@ -625,15 +628,7 @@ static int kcopyd_init(void)
return r;
}
_kcopyd_wq = create_singlethread_workqueue("kcopyd");
if (!_kcopyd_wq) {
jobs_exit();
mutex_unlock(&kcopyd_init_lock);
return -ENOMEM;
}
kcopyd_clients++;
INIT_WORK(&_kcopyd_work, do_work);
mutex_unlock(&kcopyd_init_lock);
return 0;
}
@ -644,8 +639,6 @@ static void kcopyd_exit(void)
kcopyd_clients--;
if (!kcopyd_clients) {
jobs_exit();
destroy_workqueue(_kcopyd_wq);
_kcopyd_wq = NULL;
}
mutex_unlock(&kcopyd_init_lock);
}
@ -662,15 +655,31 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
kc = kmalloc(sizeof(*kc), GFP_KERNEL);
if (!kc) {
r = -ENOMEM;
kcopyd_exit();
return -ENOMEM;
return r;
}
spin_lock_init(&kc->lock);
spin_lock_init(&kc->job_lock);
INIT_LIST_HEAD(&kc->complete_jobs);
INIT_LIST_HEAD(&kc->io_jobs);
INIT_LIST_HEAD(&kc->pages_jobs);
INIT_WORK(&kc->kcopyd_work, do_work);
kc->kcopyd_wq = create_singlethread_workqueue("kcopyd");
if (!kc->kcopyd_wq) {
r = -ENOMEM;
kfree(kc);
kcopyd_exit();
return r;
}
kc->pages = NULL;
kc->nr_pages = kc->nr_free_pages = 0;
r = client_alloc_pages(kc, nr_pages);
if (r) {
destroy_workqueue(kc->kcopyd_wq);
kfree(kc);
kcopyd_exit();
return r;
@ -680,6 +689,7 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
if (IS_ERR(kc->io_client)) {
r = PTR_ERR(kc->io_client);
client_free_pages(kc);
destroy_workqueue(kc->kcopyd_wq);
kfree(kc);
kcopyd_exit();
return r;
@ -699,6 +709,10 @@ void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)
/* Wait for completion of all jobs submitted by this client. */
wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
BUG_ON(!list_empty(&kc->complete_jobs));
BUG_ON(!list_empty(&kc->io_jobs));
BUG_ON(!list_empty(&kc->pages_jobs));
destroy_workqueue(kc->kcopyd_wq);
dm_io_client_destroy(kc->io_client);
client_free_pages(kc);
client_del(kc);